Heavy 7 day period a week early and red spotting (have never spotted before). have irregular cycles ranging from 25 to 38 days. not on birth control?

Reasons: Reason for this include hormones, pituitary, thyroid, weight (thin/heavy). You may want to see a doctor to have an exam and a thorough history taken, possibly laboratory tests to see if any of these apply to your situation. Again, most common reasons, though, is imbalance of Progesterone and estrogen. Best wishes.

Dr Fowler and another doctor agreed

Regularly irregular: Given the variation in your cycle frequency, there is obviously variation in terms of the different phases of your cycle. One common variation is when, exactly, you ovulate. Ovulatory problems are common, and can be related to thyroid disease and something called pcos. Talk to your doctor about the workup and possible ways to treat, such as with birth control pills.